Want these to last for future holidays and gift-givings? Write your message on a sticker, and put that in the message area of the tag. Make sure to remove the sticker soon after the gift is opened so the adhesive doesn't go all squidgy on you.
The Math:
$5 for an 8x8" swatch gets you 8 tags at about 63Â¢ each.
$10.50 for a fat quarter of the basic combed cotton gets you 45 tags at about 23Â¢ each!